/*-------------------------------------------------------------------------
 *
 * pg_operator.c--
 *    routines to support manipulation of the pg_operator relation
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /usr/local/cvsroot/postgres95/src/backend/catalog/pg_operator.c,v 1.8 1996/12/26 17:46:07 momjian Exp $
 *
 * NOTES
 *    these routines moved here from commands/define.c and somewhat cleaned up.
 *	
 *-------------------------------------------------------------------------
 */
#include <postgres.h>

#include <catalog/pg_proc.h>
#include <utils/syscache.h>
#include <access/heapam.h>
#include <parser/catalog_utils.h>
#include <catalog/catname.h>
#include <catalog/pg_operator.h>
#include <storage/bufmgr.h>
#include <fmgr.h>
#include <miscadmin.h>
#ifndef HAVE_MEMMOVE
# include <regex/utils.h>
#else
# include <string.h>
#endif

static Oid OperatorGetWithOpenRelation(Relation pg_operator_desc,
				       const char *operatorName,
				       Oid leftObjectId,
				       Oid rightObjectId );
static Oid OperatorGet(char *operatorName,
		       char *leftTypeName,
		       char *rightTypeName );

static Oid OperatorShellMakeWithOpenRelation(Relation pg_operator_desc,
					     char *operatorName, 
					     Oid leftObjectId, 
					     Oid rightObjectId );
static Oid OperatorShellMake(char *operatorName,
			     char *leftTypeName,
			     char *rightTypeName );

static void OperatorDef(char *operatorName,
			int definedOK,
			char *leftTypeName,
			char *rightTypeName,
			char *procedureName,
			uint16 precedence,
			bool isLeftAssociative,
			char *commutatorName,
			char *negatorName,
			char *restrictionName,
			char *oinName,
			bool canHash,
			char *leftSortName,
			char *rightSortName );
static void OperatorUpd(Oid baseId , Oid commId , Oid negId );
     
/* ----------------------------------------------------------------
 * 	OperatorGetWithOpenRelation
 *
 *	preforms a scan on pg_operator for an operator tuple
 *	with given name and left/right type oids.
 * ----------------------------------------------------------------
 *    pg_operator_desc	-- reldesc for pg_operator
 *    operatorName	-- name of operator to fetch
 *    leftObjectId	-- left oid of operator to fetch
 *    rightObjectId	-- right oid of operator to fetch
 */
static Oid
OperatorGetWithOpenRelation(Relation pg_operator_desc,
			    const char *operatorName,
			    Oid leftObjectId,
			    Oid rightObjectId)
{
    HeapScanDesc	pg_operator_scan;
    Oid		operatorObjectId;
    HeapTuple 		tup;
    
    static ScanKeyData	opKey[3] = {
	{ 0, Anum_pg_operator_oprname,  NameEqualRegProcedure },
	{ 0, Anum_pg_operator_oprleft,  ObjectIdEqualRegProcedure },
	{ 0, Anum_pg_operator_oprright, ObjectIdEqualRegProcedure },
    };
    
    fmgr_info(NameEqualRegProcedure,
	      &opKey[0].sk_func, &opKey[0].sk_nargs);
    fmgr_info(ObjectIdEqualRegProcedure,
	      &opKey[1].sk_func, &opKey[1].sk_nargs);
    fmgr_info(ObjectIdEqualRegProcedure,
	      &opKey[2].sk_func, &opKey[2].sk_nargs);
    
    /* ----------------
     *	form scan key
     * ----------------
     */
    opKey[0].sk_argument = PointerGetDatum(operatorName);
    opKey[1].sk_argument = ObjectIdGetDatum(leftObjectId);
    opKey[2].sk_argument = ObjectIdGetDatum(rightObjectId);
    
    /* ----------------
     *	begin the scan
     * ----------------
     */
    pg_operator_scan = heap_beginscan(pg_operator_desc,
				      0,
				      SelfTimeQual,
				      3,
				      opKey);
    
    /* ----------------
     *	fetch the operator tuple, if it exists, and determine
     *  the proper return oid value.
     * ----------------
     */
    tup = heap_getnext(pg_operator_scan, 0, (Buffer *) 0);
    operatorObjectId = HeapTupleIsValid(tup) ? tup->t_oid : InvalidOid;
    
    /* ----------------
     *	close the scan and return the oid.
     * ----------------
     */
    heap_endscan(pg_operator_scan);
    
    return
	operatorObjectId;
}

/* ----------------------------------------------------------------
 * 	OperatorGet
 *
 *	finds the operator associated with the specified name
 *	and left and right type names.
 * ----------------------------------------------------------------
 */
static Oid
OperatorGet(char *operatorName,
	    char *leftTypeName,
	    char *rightTypeName)
{
    Relation	pg_operator_desc;
    
    Oid		operatorObjectId;
    Oid 	leftObjectId = InvalidOid;
    Oid		rightObjectId = InvalidOid;
    bool	leftDefined = false;
    bool	rightDefined = false;
    
    /* ----------------
     *	look up the operator types.
     *
     *  Note: types must be defined before operators
     * ----------------
     */
    if (leftTypeName) {
	leftObjectId = TypeGet(leftTypeName, &leftDefined);
	
	if (!OidIsValid(leftObjectId) || !leftDefined)
	    elog(WARN, "OperatorGet: left type '%s' nonexistent",leftTypeName);
    }
    
    if (rightTypeName) {
	rightObjectId = TypeGet(rightTypeName, &rightDefined);
	
	if (!OidIsValid(rightObjectId) || !rightDefined)
	    elog(WARN, "OperatorGet: right type '%s' nonexistent",
		 rightTypeName);
    }
    
    if (!((OidIsValid(leftObjectId) && leftDefined) ||
	  (OidIsValid(rightObjectId) && rightDefined)))
	elog(WARN, "OperatorGet: no argument types??");
    
    /* ----------------
     *	open the pg_operator relation
     * ----------------
     */
    pg_operator_desc = heap_openr(OperatorRelationName);
    
    /* ----------------
     *	get the oid for the operator with the appropriate name
     *  and left/right types.
     * ----------------
     */
    operatorObjectId = OperatorGetWithOpenRelation(pg_operator_desc,
						   operatorName,
						   leftObjectId,
						   rightObjectId);
    
    /* ----------------
     *	close the relation and return the operator oid.
     * ----------------
     */
    heap_close(pg_operator_desc);
    
    return
	operatorObjectId;
}

/* ----------------------------------------------------------------
 * 	OperatorShellMakeWithOpenRelation
 *
 * ----------------------------------------------------------------
 */
static Oid
OperatorShellMakeWithOpenRelation(Relation pg_operator_desc,
				  char *operatorName,
				  Oid leftObjectId,
				  Oid rightObjectId)
{
    register int 	i;
    HeapTuple 		tup;
    Datum               values[ Natts_pg_operator ];
    char		nulls[ Natts_pg_operator ];
    Oid		operatorObjectId;
    TupleDesc    tupDesc;
    
    /* ----------------
     *	initialize our nulls[] and values[] arrays
     * ----------------
     */
    for (i = 0; i < Natts_pg_operator; ++i) {
	nulls[i] = ' ';
	values[i] = (Datum)NULL;	/* redundant, but safe */
    }
    
    /* ----------------
     *	initialize values[] with the type name and 
     * ----------------
     */
    i = 0;
    values[i++] =  PointerGetDatum(operatorName);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  (Datum) (uint16) 0;
    
    values[i++] = (Datum)'b';	/* fill oprkind with a bogus value */
    
    values[i++] = (Datum) (bool) 0;
    values[i++] = (Datum) (bool) 0;
    values[i++] =  ObjectIdGetDatum(leftObjectId);  /* <-- left oid */
    values[i++] =  ObjectIdGetDatum(rightObjectId); /* <-- right oid */
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    values[i++] =  ObjectIdGetDatum(InvalidOid);
    
    /* ----------------
     *	create a new operator tuple
     * ----------------
     */
    tupDesc = pg_operator_desc->rd_att;

    tup = heap_formtuple(tupDesc,
			 values,
			 nulls);
    
    /* ----------------
     *	insert our "shell" operator tuple and
     *  close the relation
     * ----------------
     */
    heap_insert(pg_operator_desc, tup);
    operatorObjectId = tup->t_oid;
    
    /* ----------------
     *	free the tuple and return the operator oid
     * ----------------
     */
    pfree(tup);
    
    return
	operatorObjectId;   
}

/* ----------------------------------------------------------------
 * 	OperatorShellMake
 *
 * 	Specify operator name and left and right type names,
 *	fill an operator struct with this info and NULL's,
 *	call heap_insert and return the Oid
 *	to the caller.
 * ----------------------------------------------------------------
 */
static Oid
OperatorShellMake(char *operatorName,
		  char *leftTypeName,
		  char *rightTypeName)
{    
    Relation 	pg_operator_desc;
    Oid		operatorObjectId;
    
    Oid 	leftObjectId = InvalidOid;
    Oid		rightObjectId = InvalidOid;
    bool 	leftDefined = false;
    bool	rightDefined = false;
    
    /* ----------------
     *	get the left and right type oid's for this operator
     * ----------------
     */
    if (leftTypeName)
	leftObjectId = TypeGet(leftTypeName, &leftDefined);
    
    if (rightTypeName)
	rightObjectId = TypeGet(rightTypeName, &rightDefined);
    
    if (!((OidIsValid(leftObjectId) && leftDefined) ||
	  (OidIsValid(rightObjectId) && rightDefined)))
	elog(WARN, "OperatorShellMake: no valid argument types??");
    
    /* ----------------
     *	open pg_operator
     * ----------------
     */
    pg_operator_desc = heap_openr(OperatorRelationName);
    
    /* ----------------
     *	add a "shell" operator tuple to the operator relation
     *  and recover the shell tuple's oid.
     * ----------------
     */
    operatorObjectId =
	OperatorShellMakeWithOpenRelation(pg_operator_desc,
					  operatorName,
					  leftObjectId,
					  rightObjectId);
    /* ----------------
     *	close the operator relation and return the oid.
     * ----------------
     */
    heap_close(pg_operator_desc);
    
    return
	operatorObjectId;
}

/* --------------------------------
 * OperatorDef
 *
 * This routine gets complicated because it allows the user to
 * specify operators that do not exist.  For example, if operator
 * "op" is being defined, the negator operator "negop" and the
 * commutator "commop" can also be defined without specifying
 * any information other than their names.  Since in order to
 * add "op" to the PG_OPERATOR catalog, all the Oid's for these
 * operators must be placed in the fields of "op", a forward
 * declaration is done on the commutator and negator operators.
 * This is called creating a shell, and its main effect is to
 * create a tuple in the PG_OPERATOR catalog with minimal
 * information about the operator (just its name and types).
 * Forward declaration is used only for this purpose, it is
 * not available to the user as it is for type definition.
 *
 * Algorithm:
 * 
 * check if operator already defined 
 *    if so issue error if not definedOk, this is a duplicate
 *    but if definedOk, save the Oid -- filling in a shell
 * get the attribute types from relation descriptor for pg_operator
 * assign values to the fields of the operator:
 *   operatorName
 *   owner id (simply the user id of the caller)
 *   precedence
 *   operator "kind" either "b" for binary or "l" for left unary
 *   isLeftAssociative boolean
 *   canHash boolean
 *   leftTypeObjectId -- type must already be defined
 *   rightTypeObjectId -- this is optional, enter ObjectId=0 if none specified
 *   resultType -- defer this, since it must be determined from
 *                 the pg_procedure catalog
 *   commutatorObjectId -- if this is NULL, enter ObjectId=0
 *                    else if this already exists, enter it's ObjectId
 *                    else if this does not yet exist, and is not
 *                      the same as the main operatorName, then create
 *                      a shell and enter the new ObjectId
 *                    else if this does not exist but IS the same
 *                      name as the main operator, set the ObjectId=0.
 *                      Later OperatorCreate will make another call
 *                      to OperatorDef which will cause this field
 *                      to be filled in (because even though the names
 *                      will be switched, they are the same name and
 *                      at this point this ObjectId will then be defined)
 *   negatorObjectId   -- same as for commutatorObjectId
 *   leftSortObjectId  -- same as for commutatorObjectId
 *   rightSortObjectId -- same as for commutatorObjectId
 *   operatorProcedure -- must access the pg_procedure catalog to get the
 *		   ObjectId of the procedure that actually does the operator
 *		   actions this is required.  Do an amgetattr to find out the
 *                 return type of the procedure 
 *   restrictionProcedure -- must access the pg_procedure catalog to get
 *                 the ObjectId but this is optional
 *   joinProcedure -- same as restrictionProcedure
 * now either insert or replace the operator into the pg_operator catalog
 * if the operator shell is being filled in
 *   access the catalog in order to get a valid buffer
 *   create a tuple using ModifyHeapTuple
 *   get the t_ctid from the modified tuple and call RelationReplaceHeapTuple
 * else if a new operator is being created
 *   create a tuple using heap_formtuple
 *   call heap_insert
 * --------------------------------
 *  	"X" indicates an optional argument (i.e. one that can be NULL)
 *  	operatorName;	 	-- operator name
 *	definedOK; 		-- operator can already have an oid?
 *  	leftTypeName;	 	-- X left type name
 *  	rightTypeName;		-- X right type name
 * 	procedureName;		-- procedure oid for operator code 
 *  	precedence; 		-- operator precedence 
 * 	isLeftAssociative;	-- operator is left associative?
 *  	commutatorName;		-- X commutator operator name
 *  	negatorName;	 	-- X negator operator name
 *  	restrictionName;	-- X restriction sel. procedure name
 *  	joinName;		-- X join sel. procedure name
 * 	canHash; 		-- possible hash operator?
 *  	leftSortName;		-- X left sort operator
 *  	rightSortName;		-- X right sort operator
 */
static void
OperatorDef(char *operatorName,
	    int definedOK,
	    char *leftTypeName,
	    char *rightTypeName,
	    char *procedureName,
	    uint16 precedence,
	    bool isLeftAssociative,
	    char *commutatorName,
	    char *negatorName,
	    char *restrictionName,
	    char *joinName,
	    bool canHash,
	    char *leftSortName,
	    char *rightSortName)
{
    register	i, j;
    Relation 	pg_operator_desc;
    
    HeapScanDesc	pg_operator_scan;
    HeapTuple 	tup;
    Buffer 	buffer;
    ItemPointerData	itemPointerData;
    char	nulls[ Natts_pg_operator ];
    char	replaces[ Natts_pg_operator ];
    Datum       values[ Natts_pg_operator ];
    Oid 	other_oid = 0;
    Oid		operatorObjectId;
    Oid		leftTypeId = InvalidOid;
    Oid		rightTypeId = InvalidOid;
    Oid		commutatorId = InvalidOid;
    Oid		negatorId = InvalidOid;
    bool 	leftDefined = false;
    bool	rightDefined = false;
    char        *name[4];
    Oid		typeId[8];
    int		nargs;
    TupleDesc   tupDesc;
    
    static ScanKeyData	opKey[3] = {
	{ 0, Anum_pg_operator_oprname, NameEqualRegProcedure },
	{ 0, Anum_pg_operator_oprleft, ObjectIdEqualRegProcedure },
	{ 0, Anum_pg_operator_oprright, ObjectIdEqualRegProcedure },
    };
    
    fmgr_info(NameEqualRegProcedure,
	      &opKey[0].sk_func, &opKey[0].sk_nargs);
    fmgr_info(ObjectIdEqualRegProcedure,
	      &opKey[1].sk_func, &opKey[1].sk_nargs);
    fmgr_info(ObjectIdEqualRegProcedure,
	      &opKey[2].sk_func, &opKey[2].sk_nargs);
    
    operatorObjectId = 	OperatorGet(operatorName,
				    leftTypeName,
				    rightTypeName);
    
    if (OidIsValid(operatorObjectId) && !definedOK)
	elog(WARN, "OperatorDef: operator \"%-.*s\" already defined",
	     NAMEDATALEN, operatorName); 
    
    if (leftTypeName)
	leftTypeId = TypeGet(leftTypeName, &leftDefined);
    
    if (rightTypeName)
	rightTypeId = TypeGet(rightTypeName, &rightDefined);
    
    if (!((OidIsValid(leftTypeId && leftDefined)) ||
	  (OidIsValid(rightTypeId && rightDefined))))
	elog(WARN, "OperatorGet: no argument types??");
    
    for (i = 0; i < Natts_pg_operator; ++i) {
	values[i] = (Datum)NULL;
	replaces[i] = 'r';
	nulls[i] = ' ';
    }
    
    /* ----------------
     * Look up registered procedures -- find the return type
     * of procedureName to place in "result" field.
     * Do this before shells are created so we don't
     * have to worry about deleting them later.
     * ----------------
     */
    memset(typeId, 0, 8 * sizeof(Oid));
    if (!leftTypeName) {
	typeId[0] = rightTypeId;
	nargs = 1;
    }
    else if (!rightTypeName) {
	typeId[0] = leftTypeId;
	nargs = 1;
    }
    else {
	typeId[0] = leftTypeId;
	typeId[1] = rightTypeId;
	nargs = 2;
    }
    tup = SearchSysCacheTuple(PRONAME,
			     PointerGetDatum(procedureName),
			     Int32GetDatum(nargs),
			     PointerGetDatum(typeId),
			      0);
    
    if (!PointerIsValid(tup))
	func_error("OperatorDef", procedureName, nargs, typeId);
    
    values[ Anum_pg_operator_oprcode-1 ] =  ObjectIdGetDatum(tup->t_oid);
    values[ Anum_pg_operator_oprresult-1 ] =
	 ObjectIdGetDatum(((Form_pg_proc)
			   GETSTRUCT(tup))->prorettype);
    
    /* ----------------
     *	find restriction
     * ----------------
     */
    if (restrictionName) { 	/* optional */
        memset(typeId, 0, 8 * sizeof(Oid)); 
	typeId[0] = OIDOID;		/* operator OID */
	typeId[1] = OIDOID;		/* relation OID */
	typeId[2] = INT2OID;		/* attribute number */
	typeId[3] = 0;			/* value - can be any type  */
	typeId[4] = INT4OID;		/* flags - left or right selectivity */
	tup = SearchSysCacheTuple(PRONAME,
				  PointerGetDatum(restrictionName),
				  Int32GetDatum(5),
				  PointerGetDatum(typeId),
				  0);
	if (!HeapTupleIsValid(tup))
	    func_error("OperatorDef", restrictionName, 5, typeId);
	
	values[ Anum_pg_operator_oprrest-1 ] = ObjectIdGetDatum(tup->t_oid);
    } else
	values[ Anum_pg_operator_oprrest-1 ] = ObjectIdGetDatum(InvalidOid);
    
    /* ----------------
     *	find join - only valid for binary operators
     * ----------------
     */
    if (joinName) { 		/* optional */
	memset(typeId, 0, 8 * sizeof(Oid));
	typeId[0] = OIDOID;		/* operator OID */
	typeId[1] = OIDOID;		/* relation OID 1 */
	typeId[2] = INT2OID;		/* attribute number 1 */
	typeId[3] = OIDOID;		/* relation OID 2 */
	typeId[4] = INT2OID;		/* attribute number 2 */
	
	tup = SearchSysCacheTuple(PRONAME,
				  PointerGetDatum(joinName),
				  Int32GetDatum(5),
				  PointerGetDatum(typeId),
				  0);
	if (!HeapTupleIsValid(tup))
	    func_error("OperatorDef", joinName, 5, typeId);
	
	values[Anum_pg_operator_oprjoin-1] = ObjectIdGetDatum(tup->t_oid);
    } else
	values[Anum_pg_operator_oprjoin-1] = ObjectIdGetDatum(InvalidOid);
    
    /* ----------------
     * set up values in the operator tuple
     * ----------------
     */
    i = 0;
    values[i++] = PointerGetDatum(operatorName);
    values[i++] = Int32GetDatum(GetUserId());
    values[i++] = UInt16GetDatum(precedence);
    values[i++] = leftTypeName ?  (rightTypeName ? 'b' : 'r') : 'l';
    values[i++] = Int8GetDatum(isLeftAssociative);
    values[i++] = Int8GetDatum(canHash);
    values[i++] = ObjectIdGetDatum(leftTypeId);
    values[i++] = ObjectIdGetDatum(rightTypeId);
    
    ++i; 	/* Skip "prorettype", this was done above */
    
    /*
     * Set up the other operators.  If they do not currently exist,
     * set up shells in order to get ObjectId's and call OperatorDef
     * again later to fill in the shells.
     */
    name[0] = commutatorName;
    name[1] = negatorName;
    name[2] = leftSortName;
    name[3] = rightSortName;
    
    for (j = 0; j < 4; ++j) {
	if (name[j]) {
	    
	    /* for the commutator, switch order of arguments */
	    if (j == 0) {
	        other_oid = OperatorGet(name[j], rightTypeName,leftTypeName);
		commutatorId = other_oid;
	    } else {
	        other_oid = OperatorGet(name[j], leftTypeName,rightTypeName);
		if (j == 1)
		    negatorId = other_oid;
	    }
	    
	    if (OidIsValid(other_oid)) /* already in catalogs */
		values[i++] = ObjectIdGetDatum(other_oid);
	    else if (strcmp(operatorName, name[j]) != 0) {
		/* not in catalogs, different from operator */
		
		/* for the commutator, switch order of arguments */
		if (j == 0) {
		    other_oid = OperatorShellMake(name[j],
						  rightTypeName,
						  leftTypeName);
		} else {
		    other_oid = OperatorShellMake(name[j],
						  leftTypeName,
						  rightTypeName);
		}
		
		if (!OidIsValid(other_oid))
		    elog(WARN,
			 "OperatorDef: can't create operator '%s'",
			 name[j]);     
		values[i++] =  ObjectIdGetDatum(other_oid);
		
	    } else /* not in catalogs, same as operator ??? */
		values[i++] = ObjectIdGetDatum(InvalidOid);
	    
	} else 	/* new operator is optional */
	    values[i++] = ObjectIdGetDatum(InvalidOid);
    }
    
    /* last three fields were filled in first */
    
    /*
     * If we are adding to an operator shell, get its t_ctid and a
     * buffer.
     */
    pg_operator_desc = heap_openr(OperatorRelationName);
    
    if (operatorObjectId) {
	opKey[0].sk_argument = PointerGetDatum(operatorName);
	opKey[1].sk_argument = ObjectIdGetDatum(leftTypeId);
	opKey[2].sk_argument = ObjectIdGetDatum(rightTypeId);
	
	pg_operator_scan = heap_beginscan(pg_operator_desc,
					  0,
					  SelfTimeQual,
					  3,
					  opKey);
	
	tup = heap_getnext(pg_operator_scan, 0, &buffer);
	if (HeapTupleIsValid(tup)) {
	    tup = heap_modifytuple(tup,
				   buffer,
				   pg_operator_desc,
				   values,
				   nulls,
				   replaces);
	    
	    ItemPointerCopy(&tup->t_ctid, &itemPointerData);
	    setheapoverride(true);
	    (void) heap_replace(pg_operator_desc, &itemPointerData, tup);
	    setheapoverride(false);
	} else
	    elog(WARN, "OperatorDef: no operator %d", other_oid);
	
	heap_endscan(pg_operator_scan);
	
    } else {
	tupDesc = pg_operator_desc->rd_att;
	tup = heap_formtuple(tupDesc, values, nulls);
	
	heap_insert(pg_operator_desc, tup);
	operatorObjectId = tup->t_oid;
    }
    
    heap_close(pg_operator_desc);
    
    /*
     *  It's possible that we're creating a skeleton operator here for
     *  the commute or negate attributes of a real operator.  If we are,
     *  then we're done.  If not, we may need to update the negator and
     *  commutator for this attribute.  The reason for this is that the
     *  user may want to create two operators (say < and >=).  When he
     *  defines <, if he uses >= as the negator or commutator, he won't
     *  be able to insert it later, since (for some reason) define operator
     *  defines it for him.  So what he does is to define > without a
     *  negator or commutator.  Then he defines >= with < as the negator
     *  and commutator.  As a side effect, this will update the > tuple
     *  if it has no commutator or negator defined.
     *
     *  Alstublieft, Tom Vijlbrief.
     */
    if (!definedOK)
	OperatorUpd(operatorObjectId, commutatorId, negatorId);
}

/* ----------------------------------------------------------------
 * OperatorUpd
 *
 *  For a given operator, look up its negator and commutator operators.
 *  If they are defined, but their negator and commutator operators
 *  (respectively) are not, then use the new operator for neg and comm.
 *  This solves a problem for users who need to insert two new operators
 *  which are the negator or commutator of each other.
 * ---------------------------------------------------------------- 
 */
static void
OperatorUpd(Oid baseId, Oid commId, Oid negId)
{
    register		i;
    Relation 		pg_operator_desc;
    HeapScanDesc 	pg_operator_scan;
    HeapTuple 		tup;
    Buffer 		buffer;
    ItemPointerData	itemPointerData;
    char	 	nulls[ Natts_pg_operator ];
    char	 	replaces[ Natts_pg_operator ];
    Datum               values[ Natts_pg_operator ];
    
    static ScanKeyData	opKey[1] = {
	{ 0, ObjectIdAttributeNumber, ObjectIdEqualRegProcedure },
    };
    
    fmgr_info(ObjectIdEqualRegProcedure,
	      &opKey[0].sk_func, &opKey[0].sk_nargs);
    
    for (i = 0; i < Natts_pg_operator; ++i) {
	values[i] =  (Datum)NULL;
	replaces[i] = ' ';
	nulls[i] = ' ';
    }
    
    pg_operator_desc = heap_openr(OperatorRelationName);
    
    /* check and update the commutator, if necessary */
    opKey[0].sk_argument = ObjectIdGetDatum(commId);
    
    pg_operator_scan = heap_beginscan(pg_operator_desc,
				      0,
				      SelfTimeQual,
				      1,
				      opKey);
    
    tup = heap_getnext(pg_operator_scan, 0, &buffer);
    
    /* if the commutator and negator are the same operator, do one update */
    if (commId == negId) {
	if (HeapTupleIsValid(tup)) {
	    OperatorTupleForm t;
	    
	    t = (OperatorTupleForm) GETSTRUCT(tup);
	    if (!OidIsValid(t->oprcom)
		|| !OidIsValid(t->oprnegate)) {
		
		if (!OidIsValid(t->oprnegate)) {
		    values[Anum_pg_operator_oprnegate - 1] =
			ObjectIdGetDatum(baseId);
		    replaces[ Anum_pg_operator_oprnegate - 1 ] = 'r';
		}
		
		if (!OidIsValid(t->oprcom)) {
		    values[Anum_pg_operator_oprcom - 1] =
			ObjectIdGetDatum(baseId);
		    replaces[ Anum_pg_operator_oprcom - 1 ] = 'r';
		}
		
		tup = heap_modifytuple(tup,
				       buffer,
				       pg_operator_desc,
				       values,
				       nulls,
				       replaces);
		
		ItemPointerCopy(&tup->t_ctid, &itemPointerData);
		
		setheapoverride(true);
		(void) heap_replace(pg_operator_desc, &itemPointerData, tup);
		setheapoverride(false);

	    }
	}
	heap_endscan(pg_operator_scan);
	
	heap_close(pg_operator_desc);
	
	/* release the buffer properly */
	if (BufferIsValid(buffer))
	    ReleaseBuffer(buffer);

	return;
    }
    
    /* if commutator and negator are different, do two updates */
    if (HeapTupleIsValid(tup) &&
	!(OidIsValid(((OperatorTupleForm) GETSTRUCT(tup))->oprcom))) {
	values[ Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(baseId);
	replaces[ Anum_pg_operator_oprcom - 1] = 'r';
	tup = heap_modifytuple(tup,
			       buffer,
			       pg_operator_desc,
			       values,
			       nulls,
			       replaces);
	
	ItemPointerCopy(&tup->t_ctid, &itemPointerData);
	setheapoverride(true);
	(void) heap_replace(pg_operator_desc, &itemPointerData, tup);
	setheapoverride(false);
	
	values[ Anum_pg_operator_oprcom - 1 ] = (Datum)NULL;
	replaces[ Anum_pg_operator_oprcom - 1 ] = ' ';

	/* release the buffer properly */
	if (BufferIsValid(buffer))
	    ReleaseBuffer(buffer);

    }
    
    /* check and update the negator, if necessary */
    opKey[0].sk_argument = ObjectIdGetDatum(negId);
    
    pg_operator_scan = heap_beginscan(pg_operator_desc,
				      0,
				      SelfTimeQual,
				      1,
				      opKey);
    
    tup = heap_getnext(pg_operator_scan, 0, &buffer);
    if (HeapTupleIsValid(tup) &&
	!(OidIsValid(((OperatorTupleForm) GETSTRUCT(tup))->oprnegate))) {
	values[Anum_pg_operator_oprnegate-1] = ObjectIdGetDatum(baseId);
	replaces[ Anum_pg_operator_oprnegate - 1 ] = 'r';
	tup = heap_modifytuple(tup,
			       buffer,
			       pg_operator_desc,
			       values,
			       nulls,
			       replaces);
	
	ItemPointerCopy(&tup->t_ctid, &itemPointerData);
	
	setheapoverride(true);
	(void) heap_replace(pg_operator_desc, &itemPointerData, tup);
	setheapoverride(false);
    }

    /* release the buffer properly */
    if (BufferIsValid(buffer))
	ReleaseBuffer(buffer);

    heap_endscan(pg_operator_scan);
    
    heap_close(pg_operator_desc);
}


/* ----------------------------------------------------------------
 * OperatorCreate
 *
 * Algorithm:
 *
 *  Since the commutator, negator, leftsortoperator, and rightsortoperator
 *  can be defined implicitly through OperatorCreate, must check before
 *  the main operator is added to see if they already exist.  If they
 *  do not already exist, OperatorDef makes a "shell" for each undefined
 *  one, and then OperatorCreate must call OperatorDef again to fill in
 *  each shell.  All this is necessary in order to get the right ObjectId's 
 *  filled into the right fields.
 *
 *  The "definedOk" flag indicates that OperatorDef can be called on
 *  the operator even though it already has an entry in the PG_OPERATOR
 *  relation.  This allows shells to be filled in.  The user cannot
 *  forward declare operators, this is strictly an internal capability.
 *
 *  When the shells are filled in by subsequent calls to OperatorDef,
 *  all the fields are the same as the definition of the original operator
 *  except that the target operator name and the original operatorName
 *  are switched.  In the case of commutator and negator, special flags
 *  are set to indicate their status, telling the executor(?) that
 *  the operands are to be switched, or the outcome of the procedure
 *  negated.
 * 
 * ************************* NOTE NOTE NOTE ******************************
 *  
 *  If the execution of this utility is interrupted, the pg_operator
 *  catalog may be left in an inconsistent state.  Similarly, if
 *  something is removed from the pg_operator, pg_type, or pg_procedure
 *  catalog while this is executing, the results may be inconsistent.
 * ----------------------------------------------------------------
 *
 * "X" indicates an optional argument (i.e. one that can be NULL) 
 *  	operatorName;	 	-- operator name 
 *  	leftTypeName;	 	-- X left type name 
 *  	rightTypeName;	 	-- X right type name 
 *  	procedureName;	 	-- procedure for operator 
 *  	precedence; 		-- operator precedence 
 * 	isLeftAssociative; 	-- operator is left associative 
 *  	commutatorName;	 	-- X commutator operator name 
 *  	negatorName;	 	-- X negator operator name 
 *  	restrictionName;	-- X restriction sel. procedure 
 *  	joinName;	 	-- X join sel. procedure name 
 * 	canHash; 		-- operator hashes 
 *  	leftSortName;	 	-- X left sort operator 
 *  	rightSortName;	 	-- X right sort operator 
 * 
 */
void
OperatorCreate(char *operatorName,
	       char *leftTypeName,
	       char *rightTypeName,
	       char *procedureName,
	       uint16 precedence,
	       bool isLeftAssociative,
	       char *commutatorName,
	       char *negatorName,
	       char *restrictionName,
	       char *joinName,
	       bool canHash,
	       char *leftSortName,
	       char *rightSortName)
{
    Oid 	commObjectId, negObjectId;
    Oid	leftSortObjectId, rightSortObjectId;
    int	 	definedOK;
    
    if (!leftTypeName && !rightTypeName)
	elog(WARN, "OperatorCreate : at least one of leftarg or rightarg must be defined");
    
    /* ----------------
     *	get the oid's of the operator's associated operators, if possible.
     * ----------------
     */
    if (commutatorName)
	commObjectId = OperatorGet(commutatorName,  /* commute type order */
				   rightTypeName,
				   leftTypeName);
    else commObjectId = 0;
    
    if (negatorName)
	negObjectId  = OperatorGet(negatorName,
				   leftTypeName,
				   rightTypeName);
    else negObjectId = 0;
    
    if (leftSortName)
	leftSortObjectId = OperatorGet(leftSortName,
				       leftTypeName,
				       rightTypeName);
    else leftSortObjectId = 0;
    
    if (rightSortName)
	rightSortObjectId = OperatorGet(rightSortName,
					rightTypeName,
					leftTypeName);
    else rightSortObjectId = 0;
    
    /* ----------------
     *  Use OperatorDef() to define the specified operator and
     *  also create shells for the operator's associated operators
     *  if they don't already exist.
     *
     *	This operator should not be defined yet.
     * ----------------
     */
    definedOK = 0;
    
    OperatorDef(operatorName,
		definedOK,
		leftTypeName,
		rightTypeName,
		procedureName,
		precedence,
		isLeftAssociative,
		commutatorName,
		negatorName,
		restrictionName,
		joinName,
		canHash,
		leftSortName,
		rightSortName);
    
    /* ----------------
     *	Now fill in information in the operator's associated
     *  operators.
     *
     *  These operators should be defined or have shells defined.
     * ----------------
     */
    definedOK = 1; 
    
    if (!OidIsValid(commObjectId) && commutatorName)
	OperatorDef(commutatorName,
		    definedOK,   
		    leftTypeName,	/* should eventually */
		    rightTypeName,      /* commute order */  
		    procedureName,
		    precedence,
		    isLeftAssociative,
		    operatorName,	/* commutator */
		    negatorName,
		    restrictionName,
		    joinName,
		    canHash,
		    rightSortName,
		    leftSortName);
    
    if (negatorName && !OidIsValid(negObjectId))
	OperatorDef(negatorName,
		    definedOK,
		    leftTypeName,
		    rightTypeName,
		    procedureName,
		    precedence,
		    isLeftAssociative,
		    commutatorName,
		    operatorName,	/* negator */
		    restrictionName,
		    joinName,
		    canHash,
		    leftSortName,
		    rightSortName);
    
    if (leftSortName && !OidIsValid(leftSortObjectId))
	OperatorDef(leftSortName,
		    definedOK,
		    leftTypeName,
		    rightTypeName,
		    procedureName,
		    precedence,
		    isLeftAssociative,
		    commutatorName,
		    negatorName,
		    restrictionName,
		    joinName,
		    canHash,
		    operatorName,	/* left sort */
		    rightSortName);
    
    if (rightSortName && !OidIsValid(rightSortObjectId))
	OperatorDef(rightSortName,
		    definedOK,
		    leftTypeName,
		    rightTypeName,
		    procedureName,
		    precedence,
		    isLeftAssociative,
		    commutatorName,
		    negatorName,
		    restrictionName,
		    joinName,
		    canHash,
		    leftSortName,
		    operatorName);	/* right sort */
}
